OFDM Transmission over Time-Varying Channel with Self Interference Cancellation

Orthogonal Frequency Division Multiplexing (OFDM) as a leading technology in 4G wireless communication shows great robustness against multipath spread, because the orthogonal subcarriers transform the frequencyselectivewideband channel into parallel flat fading narrowband sub-channels. This advantage has arose great interest into underwater OFDM transmission, since multipath spread is a significant issue in the underwater acoustic channel. However, the requirement of OFDM symbol duration smaller than the channel coherent time to maintain the orthogonality cannot be assured because offast time varying of the inherent unstable environment characteristic or node mobility with respect to the low acoustic wave speed. In this paper, we first measureinter-carrier interference and analyze the impact of Doppler scale to the matching pursuit channel estimation. Then we proposechannel equalization using aself-interference cancellation scheme based on two-step channel estimation. The effectivenessand robustness of the proposed receivers are demonstrated viasimulations.